Grinding of ammonium perchlorate to submicron size is accomplished generally by grinding in a mill referred to in the trade as SWECO (Southwestern Engineering Company). The grinding spheres used in a SWECO mill are silicon carbide or aluminum carbide. During grinding of the ammonium perchlorate moisture pick-up causes adhered or occluded moisture build-up near the spheres' surfaces which require periodic moisture removal procedures for the grinding spheres.
Presently, the method for the removal of adhered or occluded moisture from these spheres involves heating the spheres in a convection oven for 24 hours at 180.degree.-200.degree. F. The production-type, 280 gallon SWECO mill uses about 1600-2000 pounds of spheres.
The major drawback to the drying of spheres by means of a convection oven is the loss of a large amount of heat because of the necessity of having to heat the entire sphere to an elevated temperature in order for the adsorbed moisture to be driven off.
A more efficient drying or moisture removal system, particularly one which does not require that the entire spheres be heated, would be advantageous to the art which employs grinding spheres to reduce ammonium perchlorate to submicron size.
Therefore, an object of this invention is to provide a drying system whereby moisture removal is achieved without heating the entire grinding spheres to an elevated temperature.
Another object of this invention is to remove moisture from grinding spheres by a method whereby the drying time is drastically reduced.
A further object of this invention is to provide a drying method which requires a shorter residence time in the dryer and yields a greater throughput.